*{
	margin: 0;
	padding: 0;
}
.box{
	width: 900px;
	margin: 0px auto;
}
.box ul li{
	float: left;
	width: 100px;
	height: 50px;
	list-style: none;
	color: blue;
}
.box ul li a{
	text-decoration: none;
	background-color: black;
	display: block;
	line-height: 50px;
	color: darkgray;
	text-align: center;
}
.box ul li a:hover{
	color: #FFFFFF;
	
}

.navy{
	display: none;
}
.box ul li:hover .navy{
	display: block;
}
.nax{
	display: none;
}
.box ul li:hover .nax{
	display: block;
}
.nba{
	display: none;
}
.box ul li:hover .nba{
	display: block;
}